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  1. #1
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    non drive crank arm coming loose all the time

    my non drive crank arm keeps coming loose on me. i removed the bolt and put loctite on it and it still came out. i even changed my BB thinking that maybe it was the threads in that. put more loctite on and again today out she came. i'm going to try a different bolt. but is there something weired going on that i'm not aware of? this happen to anyone else
    i used to be a hot tar roofer, ya i remember that......day.

  2. #2
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    Is it square taper? Are you torquing it to the correct spec?

  3. #3
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    If you rode with it loose even once you might have worn out the interface and created some permanent slop

  4. #4
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    so you think perhaps the crank arm is the problem?
    i used to be a hot tar roofer, ya i remember that......day.

  5. #5
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    Maybe, maybe not. Its something to investigate if you find an arm with the same interface to swap in

  6. #6
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    Arm may be damaged, but try removing it and cleaning the spindle and inside the arm with acetone or isopropyl alcohol and reinstalling and tightening to the correct spec (usually around 30 ft-lbs).

  7. #7
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    Once a bolt comes loose and its been ridden until the crank arm has come loose, the bolt and crank arm will continue to come loose. The aluminum of the crank arm is softer than the steel spindle of the bottom bracket, therefore the crank arm wallows out and will not stay on the spindle. And it will continue to come loose, no matter what kind of loc-tite you use to hold the bolt in place.

    Only solution is to find a replacement crank arm - usually hard to do - or replace the crank.

    The only way that the arm will not come off is to use JB Weld, then when its time to replace the crank or BB due to damage/wear, your screwed that way too.

    You need a crank.

    If I remember tomorrow, I'll take a picture of a bike in the shop at the LBS I work at that has this issue. Bolt kept coming loose and crank arm keeps falling off. Customer kept riding it.

  8. #8
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    thanks ya'll
    i used to be a hot tar roofer, ya i remember that......day.

  9. #9
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    retaining compound can be a temporary fix

  10. #10
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    if your chainrings are shot then new crank time if not, i know at my shop we have tons of left side crank arms that we keep when someone replaces a crank try and see if your shop has a slightly used but better then yours crank arm with the same square taper orientation and same length. it may be a cheapy but it will save the expense of replacing a potentially good crankset.

  11. #11
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    Quote Originally Posted by frdfandc
    Only solution is to find a replacement crank arm - usually hard to do - or replace the crank.
    J&B sells repair grade replacement left arms for most applications, I have one on my commuter to replace to one RSX one that got damaged when I got ran over and it's been fine for almost two years now.. Bontrager/Trek also used to stock them for their brand cranks sets, IDK if they still do it's been a while since I worked at a Trek dealer. And BTI stocks Vuelta Impel left arms.

    I also wanna say FSA had some left arms you could buy separately.

    An exact match may be hard to find but left arms in themselves are not. But now days square taper SETS are so cheap you could pop for a new one and not be out to much dough.

  12. #12
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    Quote Originally Posted by big_papa_nuts
    J&B sells repair grade replacement left arms for most applications, I have one on my commuter to replace to one RSX one that got damaged when I got ran over and it's been fine for almost two years now.. Bontrager/Trek also used to stock them for their brand cranks sets, IDK if they still do it's been a while since I worked at a Trek dealer. And BTI stocks Vuelta Impel left arms.

    I also wanna say FSA had some left arms you could buy separately.

    An exact match may be hard to find but left arms in themselves are not. But now days square taper SETS are so cheap you could pop for a new one and not be out to much dough.

    I know that they are avail and have purchased some from J&B to use as replacements on customers bikes, but depending on the arm, there might not be enough off-set to properly clear the chain stay. I have ran into that issue as well more than once. Also, alot of LBS's will not accept a return on a special order part, so if it doesn't work, then your stuck with a crank arm.

  13. #13
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    Quote Originally Posted by frdfandc
    I know that they are avail and have purchased some from J&B to use as replacements on customers bikes, but depending on the arm, there might not be enough off-set to properly clear the chain stay. I have ran into that issue as well more than once. Also, alot of LBS's will not accept a return on a special order part, so if it doesn't work, then your stuck with a crank arm.
    True, but they go for a whole 15 bucks. Not a big deal, and any shop not willing to loose that to keep a customer might just suck anyways. I'd just have the shop put it on and if it didn't work it'd be on them.

    Or you could buy it at REI .

  14. #14
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    thanks guys but i just went to the LBS and they let me go diggin threw the junk parts that arnt junk pile and i found an arm.... chrome insted of black but i dont really care so i put it on and all good
    i used to be a hot tar roofer, ya i remember that......day.

  15. #15
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    Make sure to clean and dry the spindle off. Since its a press fit, you don't want it coming off again. Also make sure your torquing the retaining bolt to the correct spec.

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